package com.aat.dxfy.jiajiemi.demo1;

import java.io.FileInputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

import javax.crypto.Cipher;

/**
 * 证书组件
 * 
 * @author 梁栋
 * @version 1.0
 */
public abstract class CertificateCoder {

	/**
	 * 类型证书X509
	 */
	public static final String CERT_TYPE = "X.509";

	/**
	 * 由KeyStore获得私钥
	 * 
	 * @param keyStorePath
	 *            密钥库路径
	 * @param alias
	 *            别名
	 * @param password
	 *            密码
	 * @return PrivateKey 私钥
	 * @throws Exception
	 */
	private static PrivateKey getPrivateKeyByKeyStore(String keyStorePath, String alias, String password)
			throws Exception {

		// 获得密钥库
		KeyStore ks = getKeyStore(keyStorePath, password);

		// 获得私钥
		return (PrivateKey) ks.getKey(alias, password.toCharArray());

	}

	/**
	 * 由Certificate获得公钥
	 * 
	 * @param certificatePath
	 *            证书路径
	 * @return PublicKey 公钥
	 * @throws Exception
	 */
	private static PublicKey getPublicKeyByCertificate(String certificatePath) throws Exception {

		// 获得证书
		Certificate certificate = getCertificate(certificatePath);

		// 获得公钥
		return certificate.getPublicKey();

	}

	/**
	 * 获得Certificate
	 * 
	 * @param certificatePath
	 *            证书路径
	 * @return Certificate 证书
	 * @throws Exception
	 */
	private static Certificate getCertificate(String certificatePath) throws Exception {

		// 实例化证书工厂
		CertificateFactory certificateFactory = CertificateFactory.getInstance(CERT_TYPE);

		// 取得证书文件流
		FileInputStream in = new FileInputStream(certificatePath);

		// 生成证书
		Certificate certificate = certificateFactory.generateCertificate(in);

		// 关闭证书文件流
		in.close();

		return certificate;
	}

	/**
	 * 获得Certificate
	 * 
	 * @param keyStorePath
	 *            密钥库路径
	 * @param alias
	 *            别名
	 * @param password
	 *            密码
	 * @return Certificate 证书
	 * @throws Exception
	 */
	private static Certificate getCertificate(String keyStorePath, String alias, String password) throws Exception {

		// 获得密钥库
		KeyStore ks = getKeyStore(keyStorePath, password);

		// 获得证书
		return ks.getCertificate(alias);
	}

	/**
	 * 获得KeyStore
	 * 
	 * @param keyStorePath
	 *            密钥库路径
	 * @param password
	 *            密码
	 * @return KeyStore 密钥库
	 * @throws Exception
	 */
	private static KeyStore getKeyStore(String keyStorePath, String password) throws Exception {

		// 实例化密钥库
		KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());

		// 获得密钥库文件流
		FileInputStream is = new FileInputStream(keyStorePath);

		// 加载密钥库
		ks.load(is, password.toCharArray());

		// 关闭密钥库文件流
		is.close();

		return ks;
	}

	/**
	 * 私钥加密
	 * 
	 * @param data
	 *            待加密数据
	 * @param keyStorePath
	 *            密钥库路径
	 * @param alias
	 *            别名
	 * @param password
	 *            密码
	 * @return byte[] 加密数据
	 * @throws Exception
	 */
	public static byte[] encryptByPrivateKey(byte[] data, String keyStorePath, String alias, String password)
			throws Exception {

		// 取得私钥
		PrivateKey privateKey = getPrivateKeyByKeyStore(keyStorePath, alias, password);

		// 对数据加密
		Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, privateKey);

		return cipher.doFinal(data);

	}

	/**
	 * 私钥解密
	 * 
	 * @param data
	 *            待解密数据
	 * @param keyStorePath
	 *            密钥库路径
	 * @param alias
	 *            别名
	 * @param password
	 *            密码
	 * @return byte[] 解密数据
	 * @throws Exception
	 */
	public static byte[] decryptByPrivateKey(byte[] data, String keyStorePath, String alias, String password)
			throws Exception {

		// 取得私钥
		PrivateKey privateKey = getPrivateKeyByKeyStore(keyStorePath, alias, password);

		// 对数据加密
		Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, privateKey);

		return cipher.doFinal(data);

	}

	/**
	 * 公钥加密
	 * 
	 * @param data
	 *            待加密数据
	 * @param certificatePath
	 *            证书路径
	 * @return byte[] 加密数据
	 * @throws Exception
	 */
	public static byte[] encryptByPublicKey(byte[] data, String certificatePath) throws Exception {

		// 取得公钥
		PublicKey publicKey = getPublicKeyByCertificate(certificatePath);

		// 对数据加密
		Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, publicKey);

		return cipher.doFinal(data);

	}

	/**
	 * 公钥解密
	 * 
	 * @param data
	 *            待解密数据
	 * @param certificatePath
	 *            证书路径
	 * @return byte[] 解密数据
	 * @throws Exception
	 */
	public static byte[] decryptByPublicKey(byte[] data, String certificatePath) throws Exception {

		// 取得公钥
		PublicKey publicKey = getPublicKeyByCertificate(certificatePath);

		// 对数据加密
		Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, publicKey);

		return cipher.doFinal(data);

	}

	/**
	 * 签名
	 * 
	 * @param keyStorePath
	 *            密钥库路径
	 * @param alias
	 *            别名
	 * @param password
	 *            密码
	 * @return byte[] 签名
	 * @throws Exception
	 */
	public static byte[] sign(byte[] sign, String keyStorePath, String alias, String password) throws Exception {

		// 获得证书
		X509Certificate x509Certificate = (X509Certificate) getCertificate(keyStorePath, alias, password);

		// 构建签名，由证书指定签名算法
		Signature signature = Signature.getInstance(x509Certificate.getSigAlgName());

		// 获取私钥
		PrivateKey privateKey = getPrivateKeyByKeyStore(keyStorePath, alias, password);

		// 初始化签名，由私钥构建
		signature.initSign(privateKey);

		signature.update(sign);

		return signature.sign();
	}

	/**
	 * 验证签名
	 * 
	 * @param data
	 *            数据
	 * @param sign
	 *            签名
	 * @param certificatePath
	 *            证书路径
	 * @return boolean 验证通过为真
	 * @throws Exception
	 */
	public static boolean verify(byte[] data, byte[] sign, String certificatePath) throws Exception {

		// 获得证书
		X509Certificate x509Certificate = (X509Certificate) getCertificate(certificatePath);

		// 由证书构建签名
		Signature signature = Signature.getInstance(x509Certificate.getSigAlgName());

		// 由证书初始化签名，实际上是使用了证书中的公钥
		signature.initVerify(x509Certificate);

		signature.update(data);

		return signature.verify(sign);

	}

}